1. Field of the Invention
This invention relates to camera accessories, each self-mounted in front of a camera lens with a snaptype action and readily removable therefrom.
2. Description of Related Art
It is well known to mount filter holders in front of a camera lens. A conventional filter holder for a 35 mm camera has a rear annular externally-threaded portion and a front annular interiorly-threaded portion. The camera lens is mounted in a housing that is internally threaded forwardly of the lens. The externally-threaded rear portion of the filter holder threadedly engages the internally-threaded section of the housing. The front internally-threaded portion of the filter holder threadedly engages the externally-threaded rear portion of another conventional filter holder, thereby allowing a plurality of filter holders to be threaded into one another in axially adjacent relationship to form a stack of filter holders.
The use of threaded filter holders has not proven to be altogether desirable in practice, because of the tendency to cross the threads between adjacent filter holders, and between a filter holder and the lens housing. Rapid replacement of one or more filter holders is difficult because of the time required to unthread stacked filters from one another and from the lens housing.
To help alleviate such drawbacks, the art has proposed, for example, in U.S. Pat. No. 4,684,231, to use multi-part assemblies requiring the use of special threaded adaptors and special non-threaded filter holders. A first filter holder is snap-mounted on the adaptor. Additional filter holders are snap-mounted in front of the aforementioned filter holder. However, such snapmounted assemblies have not proven to be altogether satisfactory. The adaptor must still be threaded to the lens housing, thereby raising the possibility of cross-threading. As a separate piece, the adaptor must be individually stored, transported, mounted and dismounted, any one of which procedures tending to lead to misplacement or loss of the adaptor. Also, the lack of any threads on the filter holders prevents their being turned into close intimate contact with an adjacent camera accessory.
Snap-mounted camera accessories other than filter holders are also known. For example, multi-part lens cap assemblies are used as the outermost accessory to protect the camera lens and/or any accessories between the camera lens and the lens cap assembly from damage. The lens cap assembly includes diametrically opposed spring-biased locking tabs mounted on a cap member. The tabs engage with snap-type action an interiorly-threaded section, either on the lens housing or on a filter holder or like accessory. The tabs are mounted on the cap member for radial movement toward and away from each other, and are totally unsuitable for use on filter holders since the spring-biased tabs overlie a central region of the cap member and would block light passing through the central region of the filter.